cloud engineer
How to create a swap file.
A 2GB swap file.
dd if=/dev/zero of=/swapfile bs=1k count=2048k |
Activate.
mkswap /swapfile chmod 0600 /swapfile systemctl daemon-reload swapon /swapfile |
To make swap permanent, add to /etc/fstab.
/swapfile swap swap defaults 0 0 |
Check if swap is working.
cat /proc/swaps free -h |
Here’s how to launch a LightSail instance using Terraform. Create a main.tf file.
terraform { required_providers { aws = { version = >= 3.22.0" source = "hashicorp/aws" } } } provider "aws" { profile = "default" region = "us-east-1" } resource "aws_lightsail_instance" "yourinstance" { name = "yourinstance" availability_zone = "us-east-1a" blueprint_id = "amazon_linux_2" bundle_id = "nano_2_0" } |
To launch, run the following Terraform commands.
terraform init terraform apply |
Here’s how to build an EFS file system using Terraform. Create a main.tf file.
terraform { required_providers { aws = { version = ">= 3.22.0" source = "hashicorp/aws" } } } provider "aws" { profile = "default" region = "us-east-1" } resource "aws_efs_file_system" "efs-test" { creation_token = "efs-test" performance_mode = "generalPurpose" throughput_mode = "bursting" encrypted = "true" tags = { Name = "efs-test" } } resource "aws_efs_mount_target" "efs-mt-example" { file_system_id = aws_efs_file_system.efs-test.id subnet_id = "subnet-xxxxxxxxxxxxxxxxx" security_groups = ["sg-xxxxxxxxxxxxxxxxxx"] } |
To launch, run terraform.
terraform init terraform apply |
How to create an instance from a snapshot with alias IP and reserved IPs.
#!/bin/bash gcloud beta compute instances create jump-server \ --network-interface=aliases=10.128.1.0/24,private-network-ip=jump-server,subnet=default \ --machine-type=n1-standard-1 \`` --network-tier=PREMIUM \ --maintenance-policy=MIGRATE \ --service-account=xxxxxxxxxxxxx-compute@developer.gserviceaccount.com \ --tags=int-webserver \ --image=debian-10-buster-v20201216 \ --image-project=debian-cloud \ --boot-disk-size=20GB \ --boot-disk-type=pd-standard \ --boot-disk-device-name=jump-server-1 \ --no-shielded-secure-boot \ --shielded-vtpm \ --shielded-integrity-monitoring \ --labels=name=jump-server \ --reservation-affinity=any \ --zone=us-central1-a \ --project=airy-totality-151318 |
The default command uses –private-network-ip and –subnet options separately.
--private-network-ip 10.0.0.24 \ --subnet=default \ |
But when dealing with aliases, reserved IPs and subnets, use a single –network-interface option instead.
--network-interface=aliases=10.128.1.0/24,private-network-ip=jump-server,subnet=default \ |
Here’s how to move a VM instance from one zone to another. Moving an instance will involve destroying the instance from the source zone, and then recreating a replacement instance in the destination zone. To make the move easier, we will use a machine image to recreate the instance. We will also take advantage of the compute and IP address reservations to guarantee that we use the same IP address machine type. Some large machine types are hard to come by.
Get a list of compute and IP reservations.
gcloud compute addresses list gcloud compute reservations list |
Make reservations.
gcloud compute addresses create centos-ip-reservation --addresses 10.128.15.216 --region us-central1 --subnet default gcloud compute reservations create centos-us-central1-b --machine-type=n1-standard-1 --vm-count=1 --zone us-central1-b |
Create a machine image.
gcloud compute instances stop centos
gcloud beta compute machine-images create centos-image-00 --source-instance centos |
Delete original instance.
gcloud compute instances delete centos |
Create an instance from image in the new zone. Use the compute and ip reservations previously made.
gcloud beta compute instances create centos \ --no-address \ --private-network-ip 10.128.15.216 \ --source-machine-image=centos-image-00 \ --subnet=https://www.googleapis.com/compute/v1/projects/airy-totality-151318/regions/us-central1/subnetworks/default \ --machine-type=n1-standard-1 \ --reservation-affinity=any \ --reservation=centos-us-central1-b \ --zone=us-central1-b |
Finally, clean it up once you are done.
gcloud compute instances delete centos --zone us-central1-b gcloud compute addresses delete centos-ip-reservation gcloud compute reservations delete centos-us-central1-b --zone us-central1-b gcloud beta compute machine-images delete centos-image-00 |
After you created a backup vault, it’s time to create a backup plan. Here are a few examples.
aws backup create-backup-plan \ --cli-input-json file://backup-plan.json \ --profile default \ --region us-east-1 |
File: backup-plan.json
{ "BackupPlan": { "BackupPlanName": "efs-0123", "Rules": [ { "RuleName": "efs-0123", "TargetBackupVaultName": "efs-vault", "ScheduleExpression": "cron(0 0 ? * * *)", "StartWindowMinutes": 60, "CompletionWindowMinutes": 10080, "Lifecycle": { "DeleteAfterDays": 7 } } ] } } |
Finally, create a backup selection.
aws backup create-backup-selection \ --backup-plan-id xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx \ --cli-input-json file://backup-selection.json \ --profile poc \ --region us-east-1 |
File: backup-selection.json
{ "BackupSelection": { "SelectionName": "efs-0123", "IamRoleArn": "arn:aws:iam::xxxxxxxxxxxx:role/service-role/AWSBackupDefaultServiceRole", "Resources": [], "ListOfTags": [ { "ConditionType": "STRINGEQUALS", "ConditionKey": "aws-backup", "ConditionValue": "efs-0123" } ] } } |
Here’s how to create a backup vault in AWS Backup.
aws backup create-backup-vault --backup-vault-name my-efs-vault --profile default --region us-east-1 |
To delete a vault, run this command.
aws backup delete-backup-vault --backup-vault-name my-efs-vault --profile default --region us-east-1 |
Here’s how to create a WordPress site that’s read only. You will not be able to create, update and delete posts.
mariadb -u root -p use mysql; create user 'wpro'@'localhost' identified by 'yourpassword'; grant select on wordpress.* to 'wpro'@'localhost'; flush privileges; |
In MySQL or MariaDB, you have to terminate all commands with a semicolon.
Now edit your WordPress wp-config.php file. vim /var/www/wordpress/wp-config.php.
/** MySQL database username */ define('DB_USER', 'wpro'); /** MySQL database password */ define('DB_PASSWORD', 'yourpassword'); |
After saving the wp-config.php file, everything should work just like before, except that you will not be able to save, publish or delete posts, pages, or add or delete media files to your WordPress site. It’s working as intended.
Here’s how to copy a symbolic link which is also known as a soft link from one directory to another. A regular copy command will not work. You will need to use the -P option to copy the symbolic link from one directory to another. If omitted, the symbolic links will not be copied.
cp -P /directory1/* /directory2/ |
How to create a symbolic link.
ln -s sourcefile myfile ln -s /path/to/file myfile |
Here’s another way of creating a tar ball from a list of files.
tar -cvf backup.tar.gz a.txt b.txt c.txt d.txt e.txt |
Here’s how to view files in a tarball.
tar -tvf backup.tar.gz |